This demo uses Calendar in combination with Group module and Color Field. There are three 'Channel' type groups: online, print and physical. Three marketeers (Matt, Cindy and Kathy) are members of each of these groups. All marketeers can see all events but they can only add, edit or delete events within their own channel. Each channel has a color field which is used to visually distinguish between events. For demonstration purposes all marketing activities are viewable for anymous users too, but this is easily changed. There are many many more possibilities, e.g. different permission structures, use taxonomies, more details for events etc.
You can log in with one of these accounts and try for yourself:
matt/mark$Matt1
cindy/mark$Cindy1
kathy/mark$Kathy1